BGP Dynamic Update Peer-Groups

The BGP Dynamic Update Peer-Groups feature introduces a new algorithm that dynamically calculates and optimizes update-groups of neighbors that share the same outbound policies and can share the same update messages. In previous versions of Cisco IOS software, Border Gateway Protocol (BGP) update messages were grouped together based on peer-group configurations. This method of grouping updates limited outbound policies and specific-session configurations. The BGP Dynamic Update Peer-Group feature separates update-group replication from peer-group configuration, which improves convergence time and flexibility of neighbor configuration.

Feature History for the BGP Dynamic Update Peer-Groups Feature

Release

Modification

12.0(24)S

This feature was introduced.

12.2(18)S

This feature was integrated in Cisco IOS Release 12.2(18)S.

12.3(4)T

This feature was integrated in Cisco IOS Release 12.3(4)T.

12.2(27)SBC

This feature was integrated in Cisco IOS Release 12.2(27)SBC.

Finding Support Information for Platforms and Cisco IOS Software Images

Use Cisco Feature Navigator to find information about platform support and Cisco IOS software image support. Access Cisco Feature Navigator at http://www.cisco.com/go/fn. You must have an account on Cisco.com. If you do not have an account or have forgotten your username or password, click Cancel at the login dialog box and follow the instructions that appear.

BGP Update Generation and Dynamic Update Peer-Groups

In previous versions of Cisco IOS software, BGP update messages were grouped based on peer-group configurations. This method of grouping neighbors for BGP update message generation reduced the amount of system processing resources needed to process the routing table. This method, however, had the following limitations:

•All neighbors that shared the same peer-group configuration also had to share the same outbound routing policies.

•All neighbors had to belong to the same peer-group and address-family. Neighbors configured in different peer-groups cannot belong to different address-families.

These limitations existed to balance optimal update generation and replication against peer-group configuration. These limitations also caused the network operator to configure smaller peer-groups, which reduced the efficiency of update message generation.

The introduction of the BGP Dynamic Update Peer-Groups feature separates BGP update generation from peer-group configuration. The BGP Dynamic Update Peer-Groups feature introduces an algorithm that dynamically calculates BGP update-group membership based on outbound routing policies. This feature does not require any configuration by the network operator. Optimal BGP update message generation occurs automatically and independently. BGP neighbor configuration is no longer restricted by outbound routing policies, and update-groups can belong to different address families.

The BGP Dynamic Update Peer-Groups feature was introduced with the BGP Configuration Using Peer Templates feature. The BGP Dynamic Peer-Groups feature improves the performance of BGP update message generation. The BGP Configuration Using Peer Templates feature improves the flexibility of BGP neighbor configuration through the introduction of peer-policy and peer-session configuration templates. Peer-policy configuration templates are used to configure policy-related commands. Peer-session configuration templates are used for the configuration of general session commands. Peer configuration templates support inheritance and more robust and flexible configurations.

With the configuration of the BGP Configuration Using Templates feature and the support of the BGP Dynamic Update Peer-Groups features, the network operator no longer needs to configure peer-groups in BGP and can benefit from improved configuration flexibility and system performance. For more information about the BGP Configuration Using Templates feature, refer to the BGP Configuration Using Peer Templates document.

BGP Dynamic Update Peer-Group Configuration

The BGP Dynamic Update Peer-Group feature requires no configuration and occurs automatically. When a change to outbound policy occurs, the router automatically recalculates update-group memberships and applies the changes by triggering an outbound soft reset after a 1 minute timer expires. This behavior is designed to provide the network operator with time to change the configuration if a mistake is made. You can manually enable an outbound soft reset before the timer expires by entering the clear ip bgpip-address soft out command.

Note In Cisco IOS Release 12.0(25)S, 12.3(2)T, and prior releases the update group recalculation delay timer is set to 3 minutes.

For the best optimization of BGP update-group generation, we recommend that the network operator keeps outbound routing policy the same for neighbors that have similar outbound policies. This feature introduces new commands for monitoring and maintaining BGP update-groups. For more information about the new commands, see the section "How to Monitor and Maintain BGP Dynamic Update Peer-Groups."

•Specific update-groups can be cleared by using the index-group argument. The range of update-group index numbers is from 1 to 4294967295. Specific neighbors can be cleared by using the ip-address argument.

•Specific index numbers for update groups and information about update-group membership is displayed in the output of the show ip bgp update-group and debug ip bgp groups commands.

•If no argument is specified, this command will clear and recalculate all BGP update-groups.

Troubleshooting and Processing BGP Update-Groups

Perform this task to troubleshoot the processing of BGP update-groups:

SUMMARY STEPS

1. enable

2. debug ip bgp groups [index-group | ip-address]

DETAILED STEPS

Command or Action

Purpose

Step 1

enable

Example:

Router> enable

Enables privileged EXEC mode.

•Enter your password if prompted.

Step 2

debug ip bgp groups [index-group | ip-address]

Example:

Router# debug ip bgp groups

Displays information related to the processing of BGP update-groups.

•Debugging information about specific update-groups can be displayed by using the index-group argument. The range of update-group index numbers is from 1 to 4294967295. Debugging information about specific neighbors can be displayed by using the ip-address argument.

•If no argument is specified, debugging information about all update-groups will be displayed.

Note The output of this command can be very verbose. This command should not be deployed in a production network unless your are troubleshooting a problem.

Displaying BGP Update-Group Statistics

Perform this task to display BGP update-group statistics:

SUMMARY STEPS

1. enable

2. show ip bgp replication [index-group | ip-address]

DETAILED STEPS

Command or Action

Purpose

Step 1

enable

Example:

Router> enable

Enables higher privilege levels, such as privileged EXEC mode.

•Enter your password if prompted.

Step 2

show ip bgp replication [index-group | ip-address]

Example:

Router# show ip bgp replication

Displays BGP update-group replication statistics.

•Specific update-group replication statistics can be displayed by using the index-group argument. The range of update-group index numbers is from 1 to 4294967295. Specific update-group replication statistics can be displayed by using the ip-address argument.

•If no argument is specified, this command will display replication statistics for all update-groups.

Displaying Information About the Processing of BGP Update-Groups

Perform this task to display information related to the processing of BGP update-groups.

SUMMARY STEPS

1. enable

2. show ip bgp update-group[index-group | ip-address] [summary]

DETAILED STEPS

Command or Action

Purpose

Step 1

enable

Example:

Router> enable

Enables higher privilege levels, such as privileged EXEC mode.

•Enter your password if prompted.

Step 2

show ip bgp update-group [index-group | ip-address] [summary]

Example:

Router# show ip bgp update-group

Displays information about BGP update-groups.

•Information about specific update-group replication statistics can be displayed by using the index-group argument. The range of update-group index numbers is from 1 to 4294967295. Information about specific update-groups can be displayed by using the ip-address argument.

•If no argument is specified, this command will display replication statistics for all update-groups.

•Summary information can be displayed by using the summary keyword.

Configuration Examples for BGP Dynamic Update Peer-Groups

The following examples illustrate the configuration and verification of this feature:

Standards

No new or modified standards are supported by this feature, and support for existing standards has not been modified by this feature.

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MIBs

MIBs

MIBs Link

No new or modified MIBs are supported by this feature, and support for existing MIBs has not been modified by this feature.

To locate and download MIBs for selected platforms, Cisco IOS releases, and feature sets, use Cisco MIB Locator found at the following URL:

http://www.cisco.com/go/mibs

RFCs

RFCs

Title

No new or modified RFCs are supported by this feature, and support for existing RFCs has not been modified by this feature.

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Technical Assistance

Description

Link

The Cisco Technical Support website contains thousands of pages of searchable technical content, including links to products, technologies, solutions, technical tips, and tools. Registered Cisco.com users can log in from this page to access even more content.

Syntax Description

(Optional) Specifies that the update group with the specified index number will be reset. The range of update group index numbers is from 1 to 4294967295.

neighbor-address

(Optional) Specifies the IP address of a single peer that will be reset. The value for this argument can be an IPv4 or IPv6 address.

all

(Optional) Specifies the reset of update group members in all address families.

ipv4

(Optional) Specifies the reset of update group members in IPv4 address family sessions.

multicast

(Optional) Specifies the reset of update group members in multicast address family sessions.

mdt

(Optional) Specifies the reset of update group members in multicast distribution tree (MDT) address family sessions.

unicast

(Optional) Specifies the reset of update group members in unicast address family sessions.

ipv6

(Optional) Specifies the reset of update group members in IPv6 address family sessions.

vpnv4

(Optional) Specifies the reset of update group members in Virtual Private Network Version 4 (VPNv4) address family sessions.

vpnv6

(Optional) Specifies the reset of update group members in Virtual Private Network Version 6 (VPNv6) address family sessions.

Command Modes

Privileged EXEC

Command History

Release

Modification

12.0(24)S

This command was introduced.

12.2(18)S

This command was integrated into Cisco IOS Release 12.2(18)S.

12.3(4)T

This command was integrated into Cisco IOS Release 12.3(4)T.

12.0(29)S

The mdt keyword was added.

12.2(27)SBC

This command was integrated into Cisco IOS Release 12.2(27)SBC.

12.2(33)SRA

This command was integrated into Cisco IOS Release 12.2(33)SRA.

Usage Guidelines

The clear ip bgp update-group command is used to clear BGP update group member sessions. If no keywords or arguments are specified, entering this command will recalculate all update groups. Specific index numbers for update groups and information about update-group membership is displayed in the output of the show ip bgp update-group and debug ip bgp groups commands.

When a change to outbound policy occurs, the BGP routing process will automatically recalculate update-group memberships and apply changes by triggering an outbound soft reset after a 1-minute timer expires. This behavior is designed to provide the network operator with time to change the configuration before the soft reset is initiated. You can immediately initiate the outbound soft reset before the timer expires by entering the clear ip bgpip-address soft out command or immediately initiate a hard reset by entering the clear ip bgpip-address command.

Note In Cisco IOS Release 12.0(25)S, 12.3(2)T, and prior releases, the update group recalculation delay timer is set to 3 minutes.

Examples

In the following example, the membership of the 10.0.0.1 peer is cleared from an update group:

Router#clear ip bgp update-group 10.0.0.1

In the following example, update-group information for all peers in the index 1 update group is cleared:

Router#clear ip bgp update-group 1

In the following example, update-group information for all MDT address family session peers in the index 6 update group is cleared:

Router#clear ip bgp ipv4 mdt update-group 6

Related Commands

Command

Description

clear ip bgp

Resets a BGP connection or session.

debug ip bgp groups

Displays information related to the processing of BGP update groups.

show ip bgp replication

Displays BGP update-group replication statistics.

show ip bgp update-group

Displays information about BGP update groups.

debug ip bgp updates

To display information about the processing of Border Gateway Protocol (BGP) updates, use the debug ip bgp updates command in privileged EXEC mode. To disable the display of BGP update information, use the no form of this command.

Examples

In the following sample output, the output shows that the BGP session was cleared between neighbor 10.4.9.21 and the local router 10.4.9.4. There are no field description tables for this command because the debugging output from this command depends on the subsequent commands that are entered.

show ip bgp update-group

To display information about BGP update groups, use the show ip bgp update-groupcommand in user EXEC or privileged EXEC mode.

show ip bgp update-group [index-group | ip-address] [summary]

Syntax Description

index-group

(Optional) Displays the update group with its corresponding index number. The range of update-group index numbers is from 1 to 4294967295.

ip-address

(Optional) Displays the IP address of a single neighbor who is a member of an update group.

summary

(Optional) Displays a summary of update-group member information. The output can be filtered to show information for a single index group or peer with the index-group or ip-address argument.

Command Modes

User EXECPrivileged EXEC

Command History

Release

Modification

12.0(24)S

This command was introduced.

12.2(18)S

This command was integrated into Cisco IOS Release 12.2(18)S.

12.3(4)T

This command was integrated into Cisco IOS Release 12.3(4)T.

12.2(27)SBC

This command was integrated into Cisco IOS Release 12.2(27)SBC.

Usage Guidelines

Use this command to display information about BGP update groups. When a change to BGP outbound policy occurs, the router automatically recalculates update group memberships and applies the changes by triggering an outbound soft reset after a 1-minute timer expires. This behavior is designed to provide the network operator with time to change the configuration if a mistake is made. You can manually enable an outbound soft reset before the timer expires by entering the clear ip bgpip-address soft out command.

Note In Cisco IOS Release 12.0(25)S, 12.3(2)T, and prior releases the update group recalculation delay timer is set to 3 minutes.

Examples

The following sample output from the show ip bgp update-groupcommand shows update group information for all neighbors:

Specific peer information and statistics, including IP address and AS number.

Related Commands

Command

Description

clear ip bgp

Resets a BGP connection or session.

clear ip bgp update-group

Clears BGP update-group member sessions.

debug ip bgp groups

Displays information related to the processing of BGP update groups.

show ip bgp replication

Displays BGP update-group replication statistics.

Glossary

dynamic peer-group—Another name for an update-group.

peer-group—A group of neighbors, calculated at configuration time, that share the same outbound policies and can be replicated in the same updates.

peer-policy template—Peer policy templates are used to used group and apply the configuration of commands that are applied within specific address-families and NLRI configuration mode.

peer-session template—Peer session templates are used to group and apply the configuration of general session commands that are common to all address-family and Network Layer Reachability Information (NLRI) configuration modes.

peer-template—A configuration pattern that can be applied to neighbors that share common policies. Peer templates are reusable and support inheritance, allowing the network operator to group and apply distinct neighbor configurations for BGP neighbors that share common policies, and define very complex configuration patterns through the ability of a peer template to inherit configurations from other peer templates. There are two types of peer templates: "policy-templates" and "session-templates."

update-group—Like a peer-group, an update-group is a group of neighbors, calculated at configuration time, that share the same outbound policies and can be replicated in the same updates. However, update-groups are calculated dynamically and are not restricted by outbound policies.